> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of Olin Lathrop
> Sent: 19 August 2008 19:30
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] PIC-Friendly "serial expansion bus"
> 
> peter green wrote:
> > The other big problem with I2C is it is a PITA to do in software ...
> 
> I don't know why you say that.  IIC is all synchronous and is not
complex.
> I've done it a number of times where there wasn't a MSSP or I was
already
> using it for something else.  The only issue is the slave has to
respond
> at
> the speed of the master.  That means there are speed issues with a
> software
> slave implementation, but that doesn't make it difficult.  Doing a IIC
> master is about as easy as really very easy.  Have you looked closely
at
> the
> protocol?

I suspect Peter was referring to the slave implementation.  Now we know
the OP requires only a couple of 100 bps, a software I2C slave becomes
more practical.  Supporting 100kbit/s on a bit bashed slave tends to hog
up an awful lot of CPU cycles.

Regards

Mike

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